Which is better: Soap or hand sanitizer?

Which is better: Soap or hand sanitizer?

Your hands have lots of bumps and valleys, folds and rifts. So it's a great place for a virus to hide. And if you then touch your face, you can get the virus on your skin. But there are two very simple ways to prevent that from happening: soap and water, or hand sanitizer. So which is the best way to do it?

One of the coronavirus' protective outer surfaces is made of a lipid bilayer. These lipids are pin shaped molecules, and their heads are attracted to water, while their tails are repulsed by it. This natural arrangement makes the lipids stick loosely together—known as the hydrophobic effect.

%Molecular machinery% of the virus can break through cellular membranes and hijack our cells. But it has thousands upon thousands %of weak points where the right molecules could pry it apart. And this is where %soap comes in. A single drop of any brand of soap contains quadrillions of molecules called amphiphiles, which resemble biological lipids. Their tails, which are similarly repelled by water, compete for space with the lipids that make up the virus’s shell. But they’re just different enough to break up the regularity of the virus’s membrane, making the whole thing come crashing down.

These amphiphiles subsequently create protective bubbles around various particles, encompassing the virus's RNA and proteins. Introduce water, and the entire bubble can be easily washed away.

Hand sanitizers operate less like a crowbar and more akin to an earthquake. When you immerse a coronavirus in water, the hydrophobic effect reinforces the bonds within the membrane, providing them with strength. This effect also stabilizes the large proteins responsible for forming the spikes on the coronavirus, holding them in place and maintaining the shape that facilitates cell infection. If the virus is allowed to dry out in the air, it retains its stability.

Yet, envelop it in a high concentration of alcohol, such as the ethanol or isopropanol commonly found in hand sanitizers, and the hydrophobic effect vanishes, allowing molecules to move freely. The overall impact is comparable to removing all the nails and mortar from a house and subjecting it to an earthquake. The cell's membrane collapses, and the spike proteins crumble.

In both scenarios, the actual process of neutralizing the virus occurs within a mere second or two. However, medical experts recommend a minimum of 20 seconds for handwashing due to the intricate landscape of the hands. To provide adequate protection, soap and sanitizer must reach every part, including the palms, fingertips, outer surfaces, and spaces between the fingers.

During a coronavirus outbreak, doctors advise washing hands with soap and water whenever possible. Despite the similar efficacy of both approaches in killing the virus, soap and water offer two advantages: firstly, they wash away any dirt that could conceal virus particles, and secondly, it is more feasible to completely cover the hands with soap and water for a continuous 20 seconds. Of course, hand sanitizer is more convenient for on-the-go use. In the absence of a sink, apply the sanitizer thoroughly and rub your hands together until dry.

Regrettably, billions of people lack access to clean drinking water, a critical issue at any time and especially during an outbreak. Researchers and aid groups are actively working on solutions for these communities, such as a device that uses salt, water, and a car battery to produce chlorinated water, effectively eliminating harmful pathogens and safe for handwashing.

While soap and water are recommended whenever possible for dealing with a coronavirus, it may not necessarily be the best approach for every viral outbreak. Some common colds, caused by rhinoviruses with a capsid geometric protein structure instead of a lipid membrane, may require more time for soap to be effective. However, hand sanitizer may prove more effective in these cases, particularly if followed by handwashing to eliminate residual particles. Ultimately, the most reliable guidance for addressing any illness-related situation is to follow the advice of accredited medical professionals.